1. Field of the Invention
The present invention relates to a three way valve and more particularly to a two-position and three-way valve.
2. Description of the Prior Art
In order to maintain a fluid within a vessel at a constant pressure, the prior art used a combination of a valve actuatable in response to the fluid pressure within a predetermined range of pressure with a control. If a plurality of valves are used, such a combination requires any actuator for rapidly controlling the valves and the control together so that the amount of the fluid held within the vessel can be varied with the passage of time in any remote control manner.
One of the most general forms of such a combination comprises a plurality of regulator and valve pairs. Among them, the modern systems includes an electropneumatic analog regulator system consisting of a controller and three way valves and an on-off control system comprising, in combination, a controller connected with two inlet and outlet two-way valves through a pressure intensifier.
Although the first-mentioned regulator-valve pair system is simple in construction, it requires the number of regulator-valve combinations equal to the number of necessary settings. Thus, such a system is bulky and troublesome in operation since the settings must be manually made separately.
The electropneumatic analog regulator system can be reduced in size and set more simply, but is expensive and inferior with respect to responsibility.
Although the on-off control system is less expensive and more simple in construction than the two aforementioned prior art systems, a valve currently used therein is generally insensitive in operation so that the valve cannot be actuated rapidly in response to variable parameter to provide an increased accuracy in comparison with the two aforementioned prior art systems.